[OpenAFS] Re: Possible cache corruption with linux client and
Wed, 14 Nov 2012 14:04:38 -0500 (EST)
On Tue, 13 Nov 2012, Andrew Deason wrote:
> On Tue, 13 Nov 2012 13:58:11 -0500
> Jeffrey Altman <email@example.com> wrote:
>> If it is always 4KB at the beginning of the file I do not think
>> Andrew's patch is going to be the solution. It is certainly worth
>> trying if you can but in this scenario to get a 4KB at the beginning the
>> client would need to have issued an RXAFS_FetchData() for offset 0 and
>> length 0 and have received back 0 bytes and status info indicating that
>> the new length of the file is 4KB.
>> I believe that Andrew's patch addresses the case where a chunksize is
>> say 64KB and the client issues a read for 1KB and the file server says
>> the file is really 4KB in length. The client would show 1KB of data
>> followed by a 3KB hole.
>> Andrew, please correct me if I'm wrong.
Someone just told me how to clear linux buffer cache using
/proc/sys/vm/drop_caches, and doing that will 'fix' the file too - no need
to re-read the file from the fileserver. It looks like the problem is
between the cache manager and the Linux buffer cache. That is consistent
with the V-files in the cache apparently containing the correct data.
Richard Brittain, Research Computing Group,
Computing Services, 37 Dewey Field Road, HB6219
Dartmouth College, Hanover NH 03755